(1) Field of the Invention
The present invention relates to a file sheet dust cover for housing and protecting a file sheet. More particularly, the invention relates to a file sheet dust cover for effectively preventing damages of thin samples, such as films or preparations, inserted and held in such a file sheet, and also attachment of dusts thereonto.
(2) Related Art Statement
Formerly, Slidex Corporation has proposed dust covers of this type, for instance, in Japanese Utility Model Registration Application Laid-open No. 61-35,869.
In such a dust cover, an inlet opening is formed at one side edge of light-transmitting plastic films by sealing the films at the remaining three sides. These films cover opposite surfaces of a file sheet, respectively. When the file sheet is completely inserted into the dust cover through the inlet opening, the dust cover can protect the file sheet, in its turn, slide films held by the file sheet, from damages, and attachment of dusts.
However, since such a prior art technique has the inlet opening at one side edge of the dust cover, there are problems in that the file sheet is likely to slip off from the dust cover during handling of the cover after the file sheet is received therein, and that dusts are ready to enter the dust cover.